Preparation of freestanding graphene-based laminar membrane for clean-water intake via forward osmosis process

Feng, Yan; Yu, Chao; Zhang, Bowu; Zou, Tao; Zhao, Hongwei; Li, Jingye

doi:10.1039/c6ra27141c

Cited by 25 publications

(11 citation statements)

References 46 publications

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“…The dependence of R on the interlayer distance h shows that the nanochannel formed by the two GE layers contributes to the molecular sieving by restricting the admittance of the ions into the system. These results are also in agreement with the observations from previously reported experimental studies [252,261].…”

Section: Ion Rejectionsupporting

confidence: 94%

“…However, for the interlayer distance h = 8 Å, the monotonic increase of the water flux Jw with the concentration C indicates that ion concentration polarization effects are less severe in the free-standing GE laminates. This is in agreement with the results from the previous experimental study using reduced GE oxide membranes in FO systems [252]. As the temperature T increases, the viscosity of DS reduces, and the mass transfer rate improves.…”

Section: Water Fluxsupporting

confidence: 92%

“…In practice, CNTs, as FO membranes, are embedded in a polymer matrix and require support from a supportive layer which has an adverse effect on reducing the water flux [251]. Unlike CNTs, stacked CCG layers can withstand not having a supportive layer [252] because of their high mechanical strength [21,146]. Therefore, CCG thin films can greatly alleviate the ICP observed in conventional FO membranes [146].…”

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics simulation of graphene-based thin films for seawater desalination

Dahanayaka¹

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Since 71% of the earth's surface is covered by the sea, seawater desalination plays a pivotal role in addressing the water crisis. Membrane separation technologies, including reverse osmosis, electrodialysis, forward osmosis, pervaporation and membrane capacitive deionization, have been the recent focus for many research studies because of their simplicity and relatively low energy cost in comparison to the thermal driven distillation processes. Nanotechnology has opened a window for researching new nanomaterials which enhance desalination performance in an economical and sustainable manner. Experimental synthesis of nanomaterials with optimized desalination performance is a trial and error process, requiring considerable resources and time.Molecular dynamics (MD) simulation is an efficient method in investigating the transport behaviours at the nanoscale and thus provides a powerful tool for the design and performance analysis of graphene (GE)-based thin films. This Ph.D. thesis research aims to investigate the seawater desalination performance in capacitive deionization, FO, electronanofiltration and PV systems by adopting four GE-based nanostructures, namely, corrugated GE layers, stacked GE sheets, ionized graphene oxide (GO) layers and GO/metal organic framework (MOF) nanocomposite, via MD simulation.The surface corrugation of GE can modify its electronic, optical, mechanical and chemical properties. The seawater desalination performance through the corrugated GE nanochannel via capacitive deionization process is studied. The simulation results reveal that the corrugation of GE sheets greatly enhances the ion adsorption capacity, while adversely affecting the water flow rate in a capacitive deionization system. The strong anchoring effect existing in the regions which are bounded by crests and troughs of the upper and lower GE layers, respectively is identified to be responsible for the enhanced Abstractxviii ion removal capacity. Moreover, desalination performance of such a system depends on the entrance configuration with its entrance effect becoming more significant at a higher electric field intensity.The stacked GE membrane performance greatly depends on the membrane structural parameters such as pore size (i.e., nanoslit width), pore offset, interlayer distance and number of GE layers. The complete rejection of ions is observed in the bilayer GE laminates, as a forward osmosis membrane, for the nanoslit widths less than 9 Å. The bilayer GE membrane can accomplish a complete ion rejection and maintain a higher water flux even at a nanoslit width larger than 9 Å, when an optimum interlayer distance of 8 Å and a completely misaligned pore configurations are adopted. Overall, the GE membranes in a forward osmosis system yield a low water flux but an enhanced ion retention capability in comparison to the GE membranes in a reverse osmosis system.Ionization of the functional groups such as the carboxylic acid of a GO sheet introduces a negative charge on the membrane surface and the desalination performance t...

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Section: Ion Rejectionsupporting

confidence: 94%

Section: Water Fluxsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics simulation of graphene-based thin films for seawater desalination

Dahanayaka¹

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“…The first approach enables the good dispersion and strong attachment of the nanomaterial on the membrane surface and enhances the long‐term stability of the nanomaterial. Functionalized graphene has been reported to modify a wide range of membrane types, including MF, UF, NF, RO, and FO membranes, via this approach. For instance, Wang et al modified a PSf membrane surface by cross‐linking GO/epichlorohydrin (ECH) with O‐(carboxymethyl)‐chitosan (OCMC), where GO bound covalently to the amino groups of OCMC.…”

Section: Preparation Of Functionalized Graphene–polymer Membranesmentioning

confidence: 99%

Graphene Oxide‐Based Polymeric Membranes for Water Treatment

Xiao

Zhao

Tian

et al. 2018

Adv Materials Inter

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their energy consumption is much lower than that of thermal approaches. [3] Therefore, membrane technologies are regarded as cost-effective candidates and play an increasingly important role in the treatment of natural waters and wastewaters. [4] Membrane processes for water purification and desalination can be generally classified into microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), and emerging forward osmosis (FO) according to the pore size of the membrane and the respective rejection mechanism. The materials used to fabricate the membranes cover a wide range of polymers and inorganic materials. By far, polymeric membranes are the most widespread type due to their high processability, high flexibility, and low cost. [5][6][7] Traditional asymmetric membranes that contain only one type of polymer are mainly used for UF and a few NF applications. These membranes exhibit an asymmetric porous structure that consists of a thin nano porous active layer and a microporous underlying layer. MF membranes, however, possess a relatively symmetric micro porous structure. These porous membranes are mainly fabricated by phase inversion. For RO, FO, and most NF membranes that reject nanoscale solutes, an individual nonporous, dense, and thin polyamide (PA) active layer is normally required and is deposited onto a porous support layer to ensure a high selectivity. The active layer is prepared via interfacial polymerization (IP), while the support layer can be fabricated by phase inversion. These membranes are known as thin film composite (TFC) membranes, and the layers are comprised of different polymers. TFC membranes possess superior permeability over that of first-generation cellulose acetate membranes. [8,9] Although polymeric membranes have been widely reported in scientific studies and utilized for industrial applications, they are restricted by the inherent limitations of the material, such as a permeability/selectivity trade-off and a low fouling resistance. The current ability to control the membrane structure in both molecular-level design and fabrication process is not satisfactory. [10] In the last decade, the incorporation of nanomaterials into polymeric membranes has gained considerable attention owing to the potential of the resulting materials for overcoming the above limitations. [11,12] These advanced composite membranes have shown enhanced performance with a low loading of nanoparticles (NPs), including zeolites, [13][14][15] silica, [16][17][18][19][20][21][22] Membrane technologies for water treatment and desalination are increasingly developed and utilized to address the global challenges of water security and supply. Membrane-based separations can produce water with desirable qualities from a wide range of water sources, such as groundwater, seawater, brackish water, and wastewater. However, the membranes, which are typically made from polymers, are still restricted by their inherent limitations, including a permeability/selectivity trade-off and a high fouling prop...

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“…Graphene oxide, a two-dimensional material composed of sp 2 -hybridized carbon in a planar network decorated with oxygen-containing groups, has attracted considerable attention in water purification in recent years. − Due to the large amount of epoxy, hydroxyl, and carboxyl groups present on the surface and at the edges of the sheets, graphene oxide (GO) shows hydrophilic properties and can therefore be applied in the aqueous environment for remediation of pollutants − through filtration, , catalytic degradation, , and adsorption. , Among these techniques, adsorption has been found to be one of the most effective methods because of its wide adaptability, ease of operation, and relatively low cost . Water-soluble organic pollutants with aromatic rings and cationic atoms are particularly favorable for adsorption on GO through π–π stacking and ionic interaction.…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient Remediation of Chloridazon and Its Metabolites: The Case of Graphene Oxide Nanoplatelets

et al. 2020

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The contamination of aqueous environments by aromatic pollutants has become a global issue. Chloridazon, a herbicide considered as harmless to the ecosystem, has been widely used in recent decades and has accumulated, together with its degradation products desphenyl-chloridazon and methyl-desphenyl-chloridazon, to a non-negligible level in surface water and groundwater. To respond to the consequent necessity for remediation, in this work, we study the adsorption of chloridazon and its metabolites by graphene oxide and elucidate the underlying mechanism by X-ray photoelectron spectroscopy. We find a high adsorption capacity of 67 g kg–1 for chloridazon and establish that bonding of chloridazon to graphene oxide is mainly due to hydrophobic interaction and hydrogen bonding. These findings demonstrate the potential of graphene-based materials for the remediation of chloridazon and its metabolites from aqueous environments.

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Preparation of freestanding graphene-based laminar membrane for clean-water intake via forward osmosis process

Abstract: Here, a thin freestanding graphene oxide based laminar membrane was prepared for clean-water intake through a forward osmosis process.

Cited by 25 publications

References 46 publications

Molecular dynamics simulation of graphene-based thin films for seawater desalination

Molecular dynamics simulation of graphene-based thin films for seawater desalination

Graphene Oxide‐Based Polymeric Membranes for Water Treatment

Highly Efficient Remediation of Chloridazon and Its Metabolites: The Case of Graphene Oxide Nanoplatelets

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